Thread tension device for sewing machines



Dec., 20, 1960 E. J. HERBST ET AL 2,965,058

THREAD TENSION DEVICE FOR SEWING MACHINES Filed Sept. 18, 1958 INVENTURS EDWARD J. HERBST and Y W ATTORNEY THREAD TENSION DEVICE FOR SEWING MACHINES Edward J. Herbst, South Plainfield, and Philip W. Dulk, Union, NJ., assignors to The Singer Manufacturing Company, Elizabeth, NJ., a corporation of New Jersey Filed Sept. 18, 1958, Ser. No. 761,839

Claims. (Cl. 112-254) The present invention relates to thread tension devices for sewing machines and has for a primary object to provide a thread tension device that is substantially disposed within the confines of the frame, is simple to adjust and to release, and is economical, dependable, and durable.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which: -v

Fig. l is a vertical sectional view transversely of the head of a sewing machine having a tension device in accordance with this invention.

Fig. 2 is a fragmentary front view, partly broken away and in section, of the sewing machine of Fig. 1.

Fig. 3 is a horizontal sectional view taken substantially on the line 3-3 of Fig. 1.

The present invention is illustrated in the drawings as embodied in a sewing machine having a frame including a head 1 having a front face 1a. The open top of the head 1 is closed in the usual manner by a removable cover plate 2. The tension device is mounted in the front upper portion of the head 1 and comprises an arbor 3 mounted in an upstanding lug 4 carried by a transverse partition 4a in the top of the head 1. The lug 4 is disposed substantially centrally transversely of the head 1 and t=he arbor 3 extends beyond the front face 1a of the head 1. The arbor 3- is secured in the lug 4 by means of a set screw 5 threaded through the lug into locking engagement with the periphery of the arbor and including a stud 6 at the leading end thereof that extends into an endwise slot 7 in the arbor 3 to insure against turning of the arbor 3.

The arbor 3 has an externally threaded portion 8 intermediate its ends and an enlarged head 9 at the free end thereof outwardly of the front face 1a of the head. Threaded on the portion 8 is an adjusting nut 10 which is relatively large in diameter and has the upper portion of the periphery thereof exposed throu-gh an opening 11 in the cover plate 2. rI'he threads on the arbor 3 are multiple and have a fast lead to provide a complete range of adjustment of the tension in one revolution of the adjusting nut 10. To limit the adjustingv nut to one revolution, there is provided an anchor disc 12 having a diameter bar 13 extending through the slot 7 of the arbor 3 to secure the disc against turning on the arbor 3 while permitting movement endwise of the arbor, and having a laterally extendingarrn` 14 cooperating with a lug 15 on the inside of a sleeve portion 16 of an adjusting disc 17. The disc 17 is.- rnounted on. the ,adjustingy nutjl() for angular` adjustment relatively'thereto and, is1

f United States Patent()fv a 2,965,058 Patented Dec. 20, 1960` ice adapted to be received in a selected one of a of holes 19 in the disc 17.

Mounted on the arbor 3 adjacent to the head 9 and outwardly of the front face 1a are a pair of opposed dish-shaped tension discs 20 between which a thread lead is adapted to run for placing a tension thereon. Inwardly of the tension discs 20, there is mounted upon the arbor 3 a cup-shaped tension release element 21 having a bottom wall 22 and a cylindrical side wall 23. A beehive spring 24 is mounted on the arbor within the plurality tension release element 21. At its inner end the spring 24 reacts against the adjusting nut Y10 through the anchor disc 12 and adjusting disc 17 and at its outer end bears against the bottom wall 22 of the tension release element which in turn bears against the tension discs 20 and the head 9, thereby developing pressure between the thread engaging faces of the tension discs. The bottom wall 22 of the tension release element 21 has a diameter bar 25 disposed in the slot 7 of the arbor 3 for restraining the same against turning on the arbor 3 while permitting movement endwise of the arbor. The side wall 23 of the tension release element 21 telescopically receives the sleeve portion 16 -of the adjusting disc 17 to provide a continuous cover for the spring 24. For releasing the tension on a thread lead disposed between the discs 20,

l the tension release element 21 is provided with a laterally releasably locked thereto byapin and hole; connection l I comprising a pin 18 on the adjusting""nut 10 that is extending ange 26 on the free edge of the side wall 23. A tension release lever 27 is pivoted intermediate its ends on -the frame of the machine by a pivot screw 28 arranged on an axis perpendicular to the arbor 3. The upper end of the lever 27 is bifurcated to provide a pair of lever arms 29 that straddle `the side wall 23 of the tension release element. The opposite end of the lever 27 comprises a lever arm 30 that is biased clockwise by a spring 31 to move the arms 29 to the inoperative position. same against the action of the spring 31 is one arm of a bell crank lever 32, the opposite arm of which is engaged' by a pin 33 on the presser lifter lever 34 of the machine. Thus, when the presser lifter lever 34 is actuated to raise the presser foot, the pin 33 engages the end of the one arm of the bell crank lever, thereby pivoting the same clockwise and causing the opposite arm to engage the arm 30 of the lever 27 to pivot the lever 27 counterclockwise. Upon counterclockwise pivotal movement of the lever 27, the arms 29 at the bifurcated end thereof move inwardly of the arbor 3 and engage the flange 26 of the tension release element 21 to move the same inwardly of the arbor 3, thereby removing the bias on the tension discs 20.

That portion of the aperture 11 in the cover plate 2 in front of the adjusting nut 10 is substantially closed by the sleeve portion 16 of the adjusting discs 17 and the tension release element 21. To close that portion of the aperture 11 behind the adjusting nut 10, there is provided a closure plate 35 loosely mounted on the arbor 3 and having a ange 36. The plate 35 has a tail 37 underlying the lug 4 for preventing turning thereof. A'

lead vdisposed between the tension discs 20 is obtained. by engaging the portion of the periphery of the adjustingv nut 10 exposed through the aperturell in the cover plate; 2 and turning the same. As the nut 10 is turned, itisl movedvendwise of the arbor 3 by virtue of its threaded engagement with the arbor 3, thereby compressing 'or relaxing the spring 24 and varying the pressure between' Cooperating with the lever 30 to move the the thread engaging faces of the tension discs 20. The setting of the tension is indicated by indicia 39 on the face of the adjusting disc 17, which indicia cooperates with apointer 40 on the ange 26 of the tension release element 21. Rotation of the adjusting nut `1l) is .limited to one revolution by cooperation of the lug 1S on the adjusting disc 1'7 wit-h the anchor disc 12. To adjust the range of tension obtainable within this one revolution, the adjusting disc 17 is moved away from the adjusting nut to withdraw the pin 18 from the hole 19 in which it is seated .and the adjusting nut 10 and the adjusting disc v1 7 are then relatively adjusted angu larly after which .the fdisc 17 is .released to seat the pin 18 in the adjacent-one of the holes 19.

Numerous alterations of the structure herein disclosed will suggest themselves-to-those skilled in the art. However, it is to be understood that the present disclosure relates toa preferred embodiment of our invention which isfor purposes ofillustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of lthe invention are intended to be included within the scope of theappended claims.

Having thus described the nature of the invention, what we claim herein is:

l. In a sewing machine having a frame, a thread tension device comprising an'arbor mounted in said frame and having an externally threaded portion intermediate its ends andan enlarged head at the freeend thereof, an adjusting nut threaded on the externally `threaded portion of said Iarbor for movement endwise of said arbor upon turning of said adjusting nut, opposed `tension discs mounted on said arbor between said adjusting nut and said head, a resilient element mounted on said arbor between said adjustingnut and Vsaid tension discs and reacting against said adjusting nut to bias said tension discs against said head, a cup-shaped tension release element having a bottom wall and a cylindrical side wall,

said tension release element being mounted on said-arbor with said bottom wall disposed between'said resilient element and said tension discs and said'side wall surrounding said resilient element; a laterally extending flange lon said side wall, a lever pivotally mounted in lsaid frame and having a bifurcated 'end straddling said side wall and adapted to cooperate with rsaidtiange to move 'said tension release element endwise of said arbor upon Aactuation 'of said lever thereby to compress said resilient element `and release the bias on 'said tension discs.

2. In 'a Ysewing machine having `a frame, a thread tension `device comprising an arbor mounted in said frame and having an externally threaded portion 'intermediate its ends and an enlarged head at the Afree end thereof, an adjusting nut threaded on the externally threaded portion of said arbor for movement endwise of said arbor upon turning of said adjusting nut, opposed tension discs mounted on said arbor between said adjusting -nut and said lhead, a resilient element mounted on said arbor between said adjusting nut and said tension discs and reacting against said adjusting nut to bias said tension discs against said head, a cup-shaped tension release element having a bottom wall and a cylindrical side wall, said tension release element being mounted on said arbor with said bottom wall disposed between said resilient element and said tension discs landsaid side wall 'surrounding said resilient element, an adjusting disc mounted on rsaid arb'or between said 'resilient element and said adjusting nut, means for 'adjustably securing said adjusting disc "tosaidadjusting'nutfor rotation, means lfor limiting `rot-ation of said adjusting disc to one revolution on said arbor comprising an anho'r disc .mounted on said arbor/between said resilient element .and said adjusting disc, means `for moving said tensionreleaseelement 4 endwise of said arbor to compress said resilientelement and thereby release the bias ,on said tension discs.

3. In a sewing machine having a frame, a thread tension device comprising an arbor mounted in said frame and having an externally threaded portion intermediate its ends and an enlarged'head at the free end thereof, an adjusting nut threaded on .the externally threadedportion of said a-rbor for movement endwise of said arbor upon turning of said adjusting nut, opposed tension discs mounted on said arbor V'between said adjusting nut and said head, aresilient element mounted on said arbor between said adjusting nut and said tension discs and reacting againstsaidadjustingfnut .to bias said tension discs against said head, a tension release element disposed between said resilient element and said tension discs, and a lever for moving said tension element endwise of said arbor to compress said resilient element and thereby release the bias on said tension discs, said frame having an open upper portion and a cover plate closing the same and having an opening, said tension-device being mounted in said frame adjacent to said cover plate with a portion of the periphery of said adjusting nut exposed through said opening, said opening being elongated endwise of said -arbor to `accommodate said adjusting nut upon movement of the same endwise of said arbor.

4. In a sewing machine having a frame, a thread tension device 'comprising an arbor mounted in said frame and having an externally threaded vportion intermediate its ends and an -enlarged head at the free end thereof, an adjusting nut fthreaded on the externally threaded portion-of said rarbor'for lmovement endwise of said arbor upon turning of said adjusting nut, opposed tension discs mounted on said arbor between said adjusting nut and said head, ya resilient element mounted on vsaid arbor between said adjusting nut and said tension discs and reacting againstsaid adjusting nut to bias ysaid tension discs against said head, a tension release element disposed between said resilient element and said tension discs, and a lever for moving'said tension release element endwise of said arbor to compress said resilient element and thereby release the bias on said tension discs, said frame having an open upper portion vand a cover plate closing the same and 'having .an opening, said tension device being :mountedinsaid frame adjacent to said cover plate with aportion of the periphery of said adjusting nut exposed through said opening, said opening being elongated endwise o'f said arbor to accommodate said adjusting nut upon movement of the same endwise of said arbor, aclosure disc mounted on said arbor between said adjusting nut and said frame, means for resiliently biasing 'said closure member against said adjusting nut, and'means for securing said closure member against turning with said adjusting nut.

5. In asewing machine having a frame including -a vertically disposedV .standard carrying a bracket arm having a frontwall and an open top, a transverse partition in the Ytop rof said bracket arm, an upstanding lug carried by said Vpartition and disposed .inwardly from the front wall of said bracketfarm, a thread tension device comprising a horizontally disposed 'arbor carried by 'said lug and having a free end extending outwardly of said bracket arm beyond the front face thereof, said vbracket arm having lan opening on the front wall thereof `through which-said arbor extends, opposed tension discs mounted upon the free yend ofrsaid arbor outwardly of the front wall of the bracket arm, spring means mounted `upon said arbor `inwardly Yof saidtension discs, said spring means'bein'g .disposedsubstantially inwardly of the front wall of the Ybratiket arm and acting through said opening to bias said tension 'discs into .thread tensioning engagement, anadjus'ting .noti-mounted on said larbor inwardly of said spring means for manual adjustment endwise of said arbor and forming an abutment for said spring means for varying the action thereof upon said tension discs, and a removable cover plate for closing the open top of said bracket arm and thereby shielding and coucealing that portion of said arbor inwardly of the front wall of said bracket arm and the adjusting nut and spring mounted thereon.

References Cited in the le of this patent UNITED STATES PATENTS Ammerman Apr. 5, 1904 Johnson Oct. 13, 1942 Casas-Robert Sept. 9, 1952 Hamlett Feb. 8, 1955 Herbst July 15, 1958 

